define not 
proc( b )
  stepone := b-1;
  negativeone := 0-1;
  steptwo := stepone*negativeone;
  return steptwo
end;
define length
proc(l)
  list := l;
  len := 0;
  while not(nullp(list)) do
     len := len + 1;
     list := cdr(list)
  od;
  return len
end;
a := [1,2,3,4,5];
b := [];
c := [[1,2],[3,4],[5,6],7];
d := [[1,2]];
e := [[[[3]]]];
lengtha := length(a);
lengthb := length(b);
lengthc := length(c);
lengthd := length(d);
lengthe := length(e)
